Cocktail shaker



FIG. 1 is a perspective view of a cocktail shaker;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof.

The broken lines in the drawings depict portions of the cocktail shaker that form no part of the claimed design. 

CLAIM The ornamental design for a cocktail shaker, as shown and described. 